1. Field of the Invention
The present invention relates to a card edge connector.
2. Description of Related Art
As a technique of this type, Japanese Unexamined Patent Application Publication No. 2011-100647 discloses a card edge connector for connecting a memory module (daughterboard) to a mainboard (motherboard) of a personal computer.
Hereinafter, the configuration of a card edge connector 1 disclosed in Japanese Unexamined Patent Application Publication No. 2011-100647 will be described with reference to FIGS. 1 to 4, and the operation and problem of the card edge connector 1 will be described with reference to FIGS. 5 to 9.
(Configuration of Card Edge Connector 1: FIGS. 1 to 4)
As shown in FIG. 1, the card edge connector 1 is configured to connect a memory module 2 (daughterboard) to a mainboard 22 (motherboard) on which the card edge connector 1 is mounted.
The memory module 2 is composed of a PCB 3 (Printed Circuit Board) and a plurality of semiconductor packages 4 arranged on both surfaces of the PCB 3. The PCB 3 is formed in a rectangular shape having a contact edge 5 and a pair of side edges 6. The contact edge 5 has a plurality of terminals. Each side edge 6 has a semicircular notch 7.
As shown in FIGS. 1 to 3, the card edge connector 1 includes a housing 8, a plurality of upper-stage contacts 9, a plurality of lower-stage contacts 10, and a pair of arm members 11.
The housing 8 is made of a resin having insulating properties, and holds the plurality of upper-stage contacts 9 and the plurality of lower-stage contacts 10. The housing 8 is formed in an elongated shape depending on the number of terminals formed on the contact edge 5 of the memory module 2. The housing 8 is disposed on the mainboard 22 with the longitudinal direction of the housing 8 being parallel with the mainboard 22. The plurality of upper-stage contacts 9 and the plurality of lower-stage contacts 10, which are held by the housing 8, are soldered to the mainboard 22, so that the upper-stage contacts 9 and the lower-stage contacts 10 are fixed to the main board 22. As shown in FIGS. 2 and 3, the housing 8 has an insertion opening 12 for inserting the contact edge 5 of the memory module 2. When the contact edge 5 of the memory module 2 is inserted into the insertion opening 12 from an obliquely upward direction, the memory module 2 is held by the plurality of upper-stage contacts 9 and the plurality of lower-stage contacts 10 in the state of being inclined obliquely with respect to the mainboard 22.
The pair of arm members 11 is configured to maintain the depressed state of the memory module 2 when the memory module 2 is depressed toward the mainboard 22 in the state where the contact edge 5 of the memory module 2 is inserted into the insertion opening 12 of the housing 8 and the memory module 2 is obliquely held. As shown in FIGS. 2 and 3, the pair of arm members 11 is formed in an elongated shape such that the arm members 11 are orthogonal to the longitudinal direction of the housing 8 from the ends in the longitudinal direction of the housing 8 and are in parallel with the mainboard 22. As shown in FIG. 1, the pair of arm members 11 has a symmetrical shape with respect to the memory module 2. Each arm member 11 is formed by folding a single metal sheet.
The terms “housing direction”, “arm direction”, and “mainboard orthogonal direction” are herein defined. The “housing direction”, “arm direction”, and “mainboard orthogonal direction” are orthogonal to each other.
The term “housing direction” refers to the longitudinal direction of the housing 8 as shown in FIGS. 1 to 3. In the “housing direction”, a direction from each end in the longitudinal direction of the housing 8 toward the central portion in the longitudinal direction of the housing 8 is referred to as “housing center direction”, and a direction from the central portion in the longitudinal direction of the housing 8 toward each end in the longitudinal direction of the housing 8 is referred to as “housing anti-center direction”.
The term “arm direction” refers to the longitudinal direction of the arm members 11 as shown in FIGS. 1 to 3. In the “arm direction”, a direction from each proximal end (each end on the housing 8 side) in the longitudinal direction of the arm members 11 toward each distal end in the longitudinal direction of the arm members 11 is referred to as “arm distal end direction”, and a direction from each distal end in the longitudinal direction of the arm members 11 toward each proximal end in the longitudinal direction of the arm members 11 is referred to as “arm proximal end direction”.
The term “mainboard orthogonal direction” refers to the direction orthogonal to the mainboard 22. In the “mainboard orthogonal direction”, a direction approaching the mainboard 22 is referred to as “mainboard approaching direction”, and a direction away from the mainboard 22 is referred to as “mainboard separating direction”.
Referring next to FIG. 4, the arm members 11 will be described in detail. As described above, the pair of arm members 11 has a symmetrical shape with respect to the memory module 2. Only the arm member 11 illustrated in the state of being dismounted from the housing 8 in FIG. 3 will be described below, and the description of the other arm member 11 will be omitted.
As shown in FIG. 4, the arm member 11 is mainly composed of a fixing portion 13, a spring portion 14, and a press-fitting portion 15. The fixing portion 13 has an SMT portion 16 (Surface Mount Tab). The spring portion 14 has a latch portion 17, an interference portion 18, and a regulation portion 19.
Each of the fixing portion 13, the spring portion 14, and the press-fitting portion 15 is in such a posture that the principal plane thereof is orthogonal to the housing direction, and is formed in an elongated shape along the arm direction.
The fixing portion 13 is configured to fix the end in the arm proximal end direction of the spring portion 14 to the mainboard 22 in cooperation with the press-fitting portion 15. The SMT portion 16 of the fixing portion 13 is fixed to the mainboard 22 by soldering, for example.
The spring portion 14 is a plate spring for elastically supporting the latch portion 17 so that the latch portion 17 can be elastically displaced in a desired direction. As shown in FIG. 4, the principal plane of the spring portion 14 is in a posture orthogonal to the housing direction. Accordingly, the spring portion 14 elastically supports the latch portion 17 so that the latch portion 17 can be elastically displaced in the housing direction, when viewed along the arm direction. The spring portion 14 is disposed on the side of the housing anti-center direction when viewed from the fixing portion 13. The spring portion 14 overlaps the fixing portion 13 in the housing direction and is in parallel with the fixing portion 13. The spring portion 14 is coupled to the fixing portion 13 through a folding portion 20. Specifically, the end on the side of the arm proximal end direction of the spring portion 14 is coupled to the end on the side of the arm proximal end direction of the fixing portion 13 through the folding portion 20. Each of the latch portion 17, the interference portion 18, and the regulation portion 19 is formed at the end on the side of the arm distal end direction of the spring portion 14.
The latch portion 17 is configured to press the memory module 2, which is to be displaced toward the mainboard separating direction, toward the mainboard approaching direction. As shown in FIG. 5, the latch portion 17 includes a guide surface 17a (push-away surface) and a pressing portion 17b. The guide surface 17a is an inclined surface that is inclined to approach the mainboard toward the housing center direction when viewed along the arm proximal end direction. The pressing portion 17b is formed by being folded in the housing anti-center direction from the tip end on the side of the housing center direction of the guide surface 17a. 
The interference portion 18 is configured to detect whether the contact edge 5 of the memory module 2 is appropriately inserted into the insertion opening 12 of the housing 8. When the contact edge 5 is not appropriately inserted into the insertion opening 12, the interference portion 18 physically interferes with the side edges 6 of the PCB 3 of the memory module 2, thereby prohibiting the memory module 2 from being depressed in the mainboard approaching direction. On the other hand, when the contact edge 5 is appropriately inserted into the insertion opening 12, the interference portion 18 is housed in the notch 7 formed in the corresponding side edge 6 of the PCB 3 of the memory module 2, thereby allowing the memory module 2 to be depressed in the mainboard approaching direction.
The regulation portion 19 is configured to regulate an excessive displacement of the interference portion 18 in the housing anti-center direction.
The press-fitting portion 15 is disposed on the side of the arm proximal end direction when viewed from the spring portion 14, and is connected to the end on the side of the arm proximal end direction of the spring portion 14. When the press-fitting portion 15 is press-fit in the arm proximal end direction into a press-fitting hole 21 (see FIG. 3) formed at each end in the housing direction of the housing 8, so that the arm member 11 is held by the housing 8. That is, the arm member 11 is supported and fixed to the mainboard 22 through the SMT portion 16 of the fixing portion 13, and is supported and fixed to the housing 8 through the press-fitting portion 15.
(Operation and Problem of Card Edge Connector 1)
Referring next to FIGS. 5 to 9, the operation and problem of the above-mentioned card edge connector 1 will be described.
In the field of laptop personal computer products, for example, with the achievement of a thinner heat sink of a CPU (Central Processing Unit), while the heat sink has the greatest height of any of the components, there is a strong demand for a reduction in height of peripheral components in units of 100 microns. For example, in the card edge connector 1 shown in FIG. 1, it is preferable that no gap be left between the memory module 2 and the mainboard 22 when the memory module 2 is mounted. However, when the card edge connector 1 shown in FIG. 1 is adopted, an unavoidable gap a is left between a connector mounting surface 22a of the mainboard 22 and a module bottom surface 2a of the memory module 2 (the bottom surface of the daughterboard) as shown in FIG. 5. The reason why the gap α is left will be described below, while explaining the operation of the card edge connector 1.
FIG. 6 shows a state where the contact edge 5 of the memory module 2 is inserted into the insertion opening 12 of the housing 8 to depress the memory module 2 toward the mainboard 22, and the side edge 6 of the PCB 3 of the memory module 2 contacts the guide surface 17a of the latch portion 17 of the arm member 11.
As the memory module 2 is further depressed toward the mainboard 22 from the state shown in FIG. 6, the side edge 6 slides on the guide surface 17a as indicated by the outline arrow in FIG. 7, and the side edge 6 pushes away the latch portion 17 in the housing anti-center direction which is a direction in parallel with the connector mounting surface 22a. In FIG. 7, the position before the displacement of the latch portion 17 is indicated by the dashed line for reference.
As the memory module 2 is further depressed toward the mainboard 22 from the state shown in FIG. 7, the side edge 6 further pushes away the latch portion 17 in the housing anti-center direction. Eventually, the side edge 6 overrides the latch portion 17, and as shown in FIG. 8, the module bottom surface 2a of the memory module 2 abuts against the connector mounting surface 22a of the mainboard 22.
Herein, the distance between the pressing portion 17b of the latch portion 17 of the arm member 11 and the connector mounting surface 22a of the mainboard 22 is defined as a latch gap H1. Further, the distance between a pressed surface 2b of the memory module 2, which is a contact portion of the latch portion 17 when the memory module 2 is pressed in the mainboard approaching direction by (the pressing portion 17b of) the latch portion 17, and the module bottom surface 2a of the memory module 2 is defined as a module thickness H2.
As shown in FIG. 8, the latch gap H1 is set to be greater than the module thickness H2, that is, H1>H2. Accordingly, in the state shown in FIG. 8, a gap β is secured between the pressing portion 17b of the latch portion 17 and the pressed surface 2b of the memory module 2. The presence of the gap β allows the latch portion 17 to be restored in the housing center direction by the self elastic restoring force of the spring portion 14 as indicated by the outline arrow, without physically interfering with the side edge 6 of the PCB 3 of the memory module 2 when the module bottom surface 2a of the memory module 2 abuts against the connector mounting surface 22a of the mainboard 22.
After that, when the depression of the memory module 2 toward the mainboard 22 is released, the memory module 2 springs up in the mainboard separating direction as indicated by the outline arrow in FIG. 9, so that the pressed surface 2b of the memory module 2 contacts the pressing portion 17b. Accordingly, a further displacement of the memory module 2 in the mainboard separating direction is regulated by the latch portion 17.
As is obvious from the comparison between FIGS. 5, 8, and 9, the reason that the gap α shown in FIG. 5 is left is the same as the reason that the gap β is present. That is, the gap α is left because the latch portion 17 is allowed to be restored without any difficulty in the housing center direction by the self elastic restoring force of the spring portion 14, without physically interfering with the side edge 6 of the PCB 3 of the memory module 2 when the module bottom surface 2a of the memory module 2 abuts against the connector mounting surface 22a of the mainboard 22 as shown in FIG. 8. In other words, the gap α is indispensable for the configuration disclosed in Japanese Unexamined Patent Application Publication No. 2011-100647.
In view of the above, in order to satisfy the demand for a further reduction in height, it is an object of the present invention to provide a technique for reducing the gap between the motherboard and the daughterboard in the state where the daughterboard (corresponding to the memory module 2) is connected to the motherboard (corresponding to the mainboard 22).